Principle and process of roasting coffee beans _ purpose and method of roasting coffee _ how to roast coffee beans

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Roasting: this heat treatment causes significant chemical and physical changes in the structure and composition of raw coffee, causing the beans to darken and emit the characteristic aroma of roasted coffee.

1. The purpose of coffee roasting

The main purposes of coffee roasting are: a, aroma; B, increase the complexity of coffee; C, get color; D, form the unique flavor of coffee and so on.

2. The way coffee is roasted

According to the baking time, it can be divided into two types: fast baking and slow baking. According to the baking machine, it is divided into two types: family workshop type and industrial type. We mainly know about industrial baking.

3. The process of roasting coffee beans

The first stage of baking is endothermic, in which raw coffee beans are slowly dried until they change to a yellowish color, and the baking smells like toast or popcorn.

The second stage, commonly known as the first crack, usually occurs at about 185C, during which the coffee beans double in size, change to a light brown color and lose about 5 per cent of their weight.

The third stage is the first explosion to the second explosion, the temperature rises from 185 degrees Celsius to about 205 degrees Celsius, the color changes from light coffee to moderate coffee, and the weight loss is about 13%. This chemical process is called pyrolysis, which converts the chemical composition of coffee beans and releases carbon dioxide. The third stage is the second endothermic period, followed by the second exothermic period (exothermic), called the second explosion (second crack). The second pyrolysis occurs at about 205210 degrees Celsius, baking a medium-deep brown color, and the sound of the second explosion sounds dense and fast, and the surface of the coffee bean is covered with a layer of oil.

When ● is heated in stages in a bean dryer (usually using a large, hot rotating cylinder), the remaining water in the coffee bean cells turns into steam, prompting the rich sugars, proteins, lipids and minerals to undergo a variety of complex chemical reactions. Coffee beans begin the caramelization process at 180-200 degrees Celsius. At 185240 ℃, sugars combine with amino acids, peptides and proteins to caramelize, which is known as the "caramelization reaction" (maillard's reaction).

Caramelization is one of the most important factors affecting the flavor of coffee. After baking for 6-7 minutes, raw beans absorb a lot of heat and start the pyrolysis reaction.

Pyrolysis can last until the second explosion, although caramelization is an important process to awaken the aroma of coffee, but with the extension of baking time, some ingredients will also be carbonized to form a bad astringent bitter substance, how to get the highest caramelization. At the same time, carbonization should be reduced to the lowest point, which is the highest technical link of roasting coffee beans.

During the roasting process, the volume of coffee beans increases by at least half, while the weight of beans decreases by 1. 5%.

● roasted coffee beans brand recommendation

The freshly roasted Arabica beans of Qianjie Coffee are fully guaranteed in terms of brand and quality. And more importantly, the performance-to-price ratio is extremely high, each pack of 227 grams, the price is only 70-90 yuan or so. According to the calculation of 15 grams of coffee beans per cup of coffee, a bag of coffee can make 15 cups of coffee, which costs only about 5 or 6 yuan per cup, which is recommended by conscience compared to the price sold in cafes for dozens of yuan a cup.

Qianjie coffee: Guangzhou bakery, the store is small but a variety of beans, you can find a variety of unknown beans, but also provide online store services. Https://shop104210103.taobao.com